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the header joist may be a single member the same galvanized sheet). Roof dead loads are limited <br />size as the ceiling joist or rafter. Single trimmer to a maximum of 15 pounds per square foot <br />joists may be used to carry a single header joist unless the additional bracing provisions of <br />that is located within 3’ of the trimmer joist R301.2.2.2.1 are provided. <br /> <br />bearing. Trimmer and header rafters shall be <br />ATTIC VENTILATION: <br />37. IRC Section R806, <br />doubled and of sufficient size to support all loads <br />HCC 5-71(15) Unvented Attic Spaces. <br />when the span of the header exceeds 4’. Approved <br />Enclosed attics and rafter spaces shall have <br />hangers shall be used when the span exceeds 6’. <br />cross ventilation. For each separate space, the <br />Tail joists over 12’ long shall be supported at the <br />total net free ventilating area shall not be less <br />header by framing anchors or on ledger strips not <br />than 1 to 150 of the area of the space <br />less than 2” x 2”. <br />ventilated, the total area is permitted to be <br /> <br />CEILING JOISTS: <br />34. IRC Sections R802.4, R802.8, <br />reduced to 1 to 300, provided at least 50% and <br />% <br />not more than 80of the required ventilating <br />and R802.8.1 Ceiling joist spans shall be in <br />accordance with IRC Tables R802.4(1) and area is located in the upper portion of the space <br />R802.4(2) or specifically designed for applied to be ventilated at least 3’ above eave or <br />loads. Rafters and ceiling joists having a cornice vents with the balance of the required <br />depth–to-thickness ratio exceeding 5 to 1 shall be ventilation provided by eave or cornice vents. <br />provided with lateral support at points of bearing Vent openings shall be provided with corrosion <br />to prevent rotation. Rafters and ceiling resistant wire mesh with 1/8” minimum to ¼” <br />joists having a depth-to-thickness ratio exceeding maximum openings. A minimum of 1-inch <br />6 to 1 shall be supported laterally by solid blocking, airspace must be maintained between the <br />diagonal bridging (wood or metal) or continuous 1” insulation and the roof sheathing at the <br />x 3” wood strip nailed across the rafter ceiling locations of the vents. <br />joists at intervals not exceeding 8’. IBC Sec. 1203.2.2 has been added to allow attic <br /> <br />space to be unvented when the design <br />ROOF SHEATHING: <br />35. IRC Section R803. <br />professional determines it would be beneficial to <br />Allowable spans for lumber used as roof sheathing <br />eliminate ventilation openings to reduce salt- <br />shall conform to Table R803.1 Spaced lumber <br />laden air and maintain relative humidity 60 <br />sheathing (“skip sheathing”) is prohibited in <br />percent or lower to: <br />Seismic Design Categories D. and E. Wood <br />2 <br />structural panels shall be identified by grade mark <br />(1) Avoid corrosion to steel components, <br />or certificate of inspection issued by an approved <br />(2) Avoid moisture condensation in the attic <br />agency and shall comply with the grades and <br />space, or <br />spans specified in Table R503.2.1.1(1). <br />(3) Minimize energy consumption for air <br /> <br />conditioning or ventilation by <br />ROOF DRAINAGE & COVERING <br />36. <br />maintaining satisfactory space <br />IRC Section R801.3, R903, R904, R905. All <br />conditions in both the attic and occupied <br />structures shall have a controlled method of water <br />space below.” <br />collection and/or disposal from roofs (typically <br /> <br />gutters). Water shall discharge to an approved <br />CHIMNEY HEIGHT: <br />38. IRC R1003.9, <br />collection or drainage system or to splash blocks <br />R1003.20. <br />where a drainage system is not required. Roofs <br />Chimneys shall extend at least 2’ higher than <br />that do not drain over edges shall have roof drains <br />any portion of a building within 10', but shall not <br />installed at the low point of the roof as well as <br />be less than 3’ above the highest point where <br />overflow drains. See IRC R903.4. Roof slope shall <br />the chimney passes through the roof. <br />be indicated on the plans and selected roof <br />Chimneys shall be provided with crickets <br />covering must be appropriate for the roof pitch. <br />when the dimension parallel to the ridgeline is <br />Roof coverings must be installed in accordance <br />greater than 30” and does not intersect the <br />with the manufacturer’s installation instructions. <br />ridgeline. The cricket and chimney shall be built <br />Flashing shall be installed at wall & roof <br />& flashed according to Figure R1003.20 and <br />intersections, at changes in roof slope or direction, <br />Table R1003.20. <br />and around roof openings. Where flashing is <br /> <br />metal, the metal shall be corrosion- resistant with a <br />minimum thickness of 0.019 inch (No. 26 <br />The County of Hawai‘i is an Equal Opportunity Provider and Employer <br /> <br /> <br />101 Pauahi Street, Suite 107 74-5044 Ane Keohoklole Hwy <br />ā <br />Hilo, Hawai‘i 96720 Kailua-Kona, Hawai’i 96740 <br /> <br />Tel: (808) 961-8331 Page 16 Tel: (808) 323-4720 <br /> <br />